The present invention relates generally to methods for forming integrated circuit chips, and more particularly, to a method for creating a high density isolation trench by means of an orientation-dependent etch and for precisely controlling a depth of polishing on the resulting textured surface.
An integrated circuit chip comprises an array of devices formed in a semiconductor substrate, with the contacts for these devices interconnected by patterns of conductive wires. An important aspect of the processing of integrated circuit chips entails the formation of isolation regions around active regions where active devices such as transistors will be formed. The formation of such isolation regions can be a complicated process involving one or more masking steps A particular problem in such processes arises in the various polishing steps utilized in the processing of integrated circuit chips. This problem arises because it is very difficult to precisely determine to within a few angstroms when a desired depth has been reached by the polishing process.